Refrigerating apparatus



March 6, 1962 J. w. JACOBS REFRIGERATING APPARATUS Filed NOV. 16, 1959ll Fig 1.;

IN V EN TOR.

[m w S. w W H 3,023,589 REFRIGERATING APPARATUS James W. Jacobs, Dayton,Ohio, assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Filed Nov. 16, 1959, Ser. No. 853,084 7 Claims.(Cl. 62-156) This invention relates to refrigerating apparatus and moreparticularly to a household refrigerator having an improved defrostcontrol system.

It is an object of this invention to provide a defrost control whicheliminates the need for a time clock or the like for periodicallyinitiating the defrost cycle.

More particularly, it is an object of this invention to provide arefrigerating system which is so designed that changes in thetemperature of an accumulator located at the outlet of the evaporatorcan be utilized for initiating a defrost cycle.

Further objects and advantages of the present invention will be apparentfrom the following description,

reference being had to the accompanying drawing wherein a preferredembodiment of the present invention is clearly shown.

In the drawing:

FIGURE 1 schematically shows a household refrigerator embodying myinvention.

FIGURE 2 is a schematic view of the refrigerant circuit shown in FIGURE1.

FIGURE 3 shows a circuit diagram for the electrical controls.

Referring now to the drawing wherein a preferred embodiment of theinvention has been shown, reference numeral 5 designates the cabinet ofa household refrigerator having anabove freezing temperature foodstorage compartment 6, at below freezing food storage compartment 7, amachinery compartment 8, and an evaporator compartment 9. I

The refrigerating system includes a conventional sealed motor compressorunit which is adapted to compress the refrigerant vapor and to dischargethe compressed vapor into a condenser 12 wherein the refrigerant isconverted into a liquid before entering a capillary tube restrictor 14.The outlet of the capillary tube 14 is connected to an evaporator 16which serves to cool the air for the compartments 6 and 7 in a manner tobe explained more fully hereinafter.

The design of the refrigerating system and the quantity of refrigerantplaced in the system is such that during normal operating conditions,all of the liquid refrigerant becomes vaporized in the evaporator 16before returning to the compressor 10. It has been found that anexcessive accumulation of frost on the evaporator 16 causes its heatabsorbing characteristics to be altered so that it operates at a lowertemperature than normal. When the evaporator temperature is thuslowered, the quantity of liquid refrigerant in the evaporator increasesto a point where some of the liquid refrigerant spills over into theaccumulator 18 located at the outlet of the evaporator. When this takesplace, the temperature of the accumulator 18 drops in temperature andthis drop in temperature is used to initiate a defrost cycle.

Under normal operating conditions the compressor 10 is cycled by meansof a thermostat assembly 26 which includes a temperature sensing bulb 22arranged in thermal exchange relationship with the evaporator 16. Thisthermostat assembly is adapted to close the switch 32 so as to energizethe compressor 10 whenever the temperature of the evaporator 16 exceedsa temperature of 12 F. and is adapted to open the switch 32 so as todeenergize the 3,923,589 Patented Mar. 6, 1962 compressor 10 wheneverthe temperature of the evaporator 16 falls below 6 F.

A defrost control thermostat assembly 24, which includes a temperaturesensing bulb 26 is arranged to sense the temperature of the accumulator18. The thermostat assembly serves to actuate the switch 28 so as todeenergize the compressor 10 when the temperature of the accumulatordrops below 6 F. At this temperature, the switch 28 moves from its fullline position, shown in FIGURE 3, to the dotted line position, in whichlatter position a circuit is closed to an electric heater 30 arranged inthermal exchange relationship with the evaporator 16 so as to causedefrosting of the evaporator. The switch 28 remains in its dotted lineposition until the temperature of the accumulator 18 reaches 50 F., atwhich time, the circuit to the electric heater is opened by the switch28 and the circuit to the motor compressor unit 10 is reestablished.

Reference numeral '40 designates an electric motor which serves tooperate a condenser fan 42 and an evaporater fan or blower 44. Asindicated in FIGURE 3 of the drawing, the motor 40 is connected inparallel with the compressor motor 10 so as to operate in unison withthe compressor 10.

As indicated in FIGURE 1 of the drawing, the evaporator 16 serves torefrigerate air for both the frozen food storage compartment 7 and theabove freezing food storage'compartment 6. The quantity of aircirculated and the temperature of the air leaving the evaporator 16 issuflicient to maintain the contents of the frozen food storagecompartment 7 free of frost at all times. Any frost which might formmomentarily in the food storage compartment is removed by the process ofsublimation in accordance with well known principles.

Whenever the compressor 16] is deenergized either by virtue of openingof the switch 28 or switch 32, the fan 44 will stop operation so as toavoid circulation of warm air through the frozen food compartment 7.

For purposes of illustration there is shown a cabinet in which therefrigerated air is circulated upwardly from the evaporator compartment9 through an air duct located adjacent the rear of the compartments 6and 7 and a corresponding amount of air is returned to the inlet of theevaporator blower 44 through the return air duct Which is provided withreturn air inlets 64 and 66 which for purposes of illustration have beenshown as located in the sidewalls of the compartments 6 and 7,respectively.

The temperature of the compartment 6 can be closely ,regulated by meansof a damper 52, which is arranged at the outlet of the refrigreated airsupply duct, as shown. This damper is controlled in response to changesin temperature of the thermostatic bulb 54 located in the compartment 6through the action of the damper actuator bellows 56. The thermostat 54is preferably designed to maintain the temperature in the compartment 6approximately between 35 F. and 40 F. The quantity of air and thetemperature of the air admitted into the frozen food compartment 7 ispreferably such that the temperature in this latter compartment ismaintained between approximately 5 F. and +5 F. The temperature valuesgiven herein are given for purposes of illustration and may be varied tosuit specific requirements.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In a refrigerator, the combination, a cabinet having a pair ofrefrigerated food storage compartments, a refrigeration system forcooling said compartments, said refrigerating system comprising anevaporator, a compressor, a condenser, and refrigerant flow connectionsbetween said evaporator, compressor and condenser, said refrigerant flowconnections including an accumulator at the outlet of said evaporator,circuit means controlling the operation of said compressor, a blowercirculating air for at least one of said compartments in thermalexchange relationship with said evaporator, said circuit means includinga first thermostatically operated switch means re- SpOnsiVe torefrigeration requirements for starting and stopping said compressor, asecond thermostatically operated switch means responsive to thetemperature of said accumulator for deenergizing said compressor inresponse to a predetermined decrease in temperature of said accumulator,means for defrosting said evaporator, said second thermostaticallyoperated switch means including means for initiating operation of saiddefrosting means in response to a predetermined decrease in temperatureof said accumulator.

2. In a refrigerator, the combination; a cabinet having a refrigeratedfood storage compartment; a refrigeration system comprising anevaporator, a compressor, a condenser, and refrigerant flow connectionsbetween said evaporator, compressor and condenser; and refrigerant flowconnections including an accumulator at the outlet of said evaporator;circuit means controlling the operation of said compressor; said circuitmeans including a first thermostatically operated switch meansresponsive to refrigeration requirements for starting and stopping saidcompressor and a second thermostatically operated switch meansresponsive to the temperature of said accumulator for deenergizing saidcompressor in response to a predetermined decrease in temperature ofsaid accumulator; and means for defrosting said evaporator; said secondthermostatically operated switch means including means for initiatingoperation of said defrosting means in response to a predetermineddecrease in temperature of said accumulator and for reenergizing saidcompressor in response to a predetermined increase in temperature ofsaid accumulator.

' 3. In combination; a cabinet having a pair of refrigerated foodstorage compartments, an evaporator compartment and a condensingcompartment; a refrigeration system comprising an evaporator in saidevaporator dompartment, a compressor and a condenser in said condensingcompartment, and refrigerant flow connections between said evaporator,compressor, and condensor; said refrigerant flow connections includingan accumulator at the outlet of said evaporator; a blower forcirculating air to be refrigerated in thermal exchange relationship withsaid evaporator; circuit means for controlling the operation of saidcompressor and said blower; said circuit means including a firstthermostatically operated switch means responsive to refrigerationrequirements for starting and stopping said compressor and said blowerand a second thermostatically operated switch means responsive to thetemperature of said accumulator for deenergizing said compressor inresponse to a predetermined decrease in temperature of said accumulator;means for defrosting said evaporator; said second thermostaticallyoperated means including means for initiating operation of said defrosting means in response to a predetermined decrease in temperature ofsaid accumulator.

4. In combination; a cabinet having a pair of refrigerated food storagecompartments, an evaporator compartment and a condensing compartment; arefrigeration system comprising an evaporator in said evaporatorcompartment, a compressor and a condenser in said condensingcompartment, and refrigerant flow connections between said evaporator,compressor, and condenser; said refrigerant flow connections includingan accumulator at the outlet of said evaporator; means including ablower for circulating air in thermal exchange relationship with saidevaporator and for discharging said air into said food storagecompartments; circuit means for controlling the operation of saidcompressor and said blower; said circuit means including a firstthermostatically operated switch means responsive to refrigerationrequirements for starting and stopping said compressor and said blowerand a second thermostatically operated switch means responsive to thetemperature of said accumulator for deener'gizing said compressor inresponse to a predetermined decrease in temperature of said accumulator;means for defrosting said evaporator; said second thermostaticallyoperated means including means for initiating operation of saiddefrosting means in response to a predetermined decrease in temperatureof said accumulator; damper means for varying the ratio of aircirculated by said blower to each of said compartments.

5. In combination; a cabinet having a pair of refrigerated food storagecompartments, an evaporator compartment and a condensing compartment; arefrigeration system comprising an evaporator in said evaporatorcompartment, a compressor and a condenser in said condensingcompartment, and refrigerant flow connections between said evaporator,compressor, and condenser; said refrigerant flow connections includingan accumulator at the outlet of said evaporator; means including ablower for circulating air in thermal exchange relations-hip with saidevaporator and for discharging said air into said food storagecompartments; circuit means for controlling the operation of saidcompressor and said blower; said circuit means including a firstthermostatically operated switch means responsive to refrigerationrequirements for starting and stopping said compressor and said blowerand a second thermostatically operated switch means responsive to thetemperature of said accumulator for deenergizing said compressor inresponse to a predetermined decrease in temperature of said accumulator;means for defrosting said evaporator; said second thermostaticallyoperated means included'means for initiating operation of saiddefrosting means in response to a predetermined decrease in temperatureof said accumulator; damper means for varying the ratio of aircirculated by said blower to each of said compartments; and a thermostatresponsive to the temperature in one of said compartments controllingsaid damper means.

6. In a refrigerator, the combination, a cabinet having a pair ofrefrigerated food storage compartments, a refrigeration system forcooling said compartments, said refrigerating system comprising anevaporator, a compressor, a condenser, and refrigerant flow connectionsbetween said evaporator, compressor and condenser, said refrigerant flowconnections including a conduit leading from the outlet of saidevaporator to said compressor, circuit means controlling the operationof said compressor, a blower circulating air for at least one of saidcompartments in thermal exchange relationship with said evaporator, saidcircuit means including a first thermostatically operated switch meansresponsive to the temperature produced by said evaporator for startingand stopping said compressor, a second thermostatically operated switchmeans responsive to the temperature of said conduit for deenergizingsaid compressor in response to a predetermined decrease in temperatureof said conduit, means for defrosting said evaporator, said secondthermostatically operated switch means including means for initiatingoperation of said defrosting means in response to a predetermineddecrease in temperature of said conduit.

7. In a refrigerator, the combination; a cabinet having a refrigeratedfood storage compartment; a refrigeration system comprising anevaporator, a compressor, a condenser, and refrigerant flow connectionsbetween said evaporator, compressor and condenser; said refrigerant flowconnections including an accumulator at the outlet of said evaporator;circuit means controlling the operation of said compressor; said circuitmeans including a first thermostatically operated switch meansresponsive to refrigeration requirements for starting and stopping saidcompressor and a second thermostatically operated switch meansresponsive to the temperature of said accumulator for deenergizing saidcompressor in response to a predetermined decrease in temperature ofsaid accumulator; and means energized by said second thermostat fordefrosting said evaporator; said second thermostatically operated switchmeans including means for initiating operation of said defrosting meansin response to a predetermined decrease in temperature of saidaccumulator.

References Cited in the file of this patent UNITED STATES PATENTS McCloyMay 6, 1952 R-aney Aug. 31, 1954 Murphy et a1. May 21, 1957 SlatteryAug. 12, 1958 Wurtz Dec. 9, 1958 Mann Oct. 6, 1959 Mann Nov. 17, 1959

